This invention relates to a control apparatus and a control method for a motor vehicle, and, in particular, to a control apparatus and a control method for a motor vehicle for efficiently controlling an engine power train in accordance with various information such as a running environment of the motor vehicle and the like.
A known conventional control system, for instance, as disclosed in Japanese Patent Laid Open No. Sho 62-126235, determines an operating region in accordance with a change in an operating state, that is, a change in an engine load (pressure in the intake pipe, air/fuel ratio sensor signal or the like) and a change in an engine rotational speed, for establishing compatibility between fuel economy and drivability, and reads a target air/fuel ratio value which has been set for every operating region, thereby changing the air/fuel ratio of an engine.
When the target air/fuel ratio is changed with the engine load and the engine rotational speed as parameters as in the conventional technology, a steady state condition is changed to another steady state condition. The fuel quantity is then changed during acceleration of the vehicle by which a torque variation is generated. This produces a strange feeling for the vehicle operator since the fuel quantity is changed during the acceleration. Further, when a NOx reduction catalyst is not employed, the air/fuel ratio considerably changes from an air/fuel ratio of 14.7, which is the theoretical mixture ratio, to around an air/fuel ratio of 24 for reducing a discharge quantity of NOx, by which the torque variation is further increased.
There is therefore needed a control apparatus and a control method capable of achieving compatibility between promoting the fuel economy and the drivability by eliminating torque variations which occur in changing the air/fuel ratio during a running operation of a motor vehicle.
These needs are met according to the present invention which provides a control apparatus and method including an outer environment detector for detecting the outer environment during the running of the motor vehicle, a running environment determining system for predicting a current running environment, for instance, a road incline, a road with a traffic jam, and the like, in accordance with the outer environment, a data storing device for storing data used to change an operating characteristic in accordance with the running environment, a switching system for switching the data in accordance with the running environment, a control quantity calculator for calculating a control quantity based on the data selected from the data storing device and a control actuator for controlling a control object. These systems can be implemented in either a hardware circuit, or as software applications operating on a microprocessor or the like.
It is an advantage of the present invention, constructed as described above, that the data, such as the air/fuel ratio or the like, is always switched taking into consideration the running environment in a non-steady state condition, a speed changing condition, a stopping condition, an idling condition, a operation of a shift lever, and the like. Therefore, any unpleasant feeling for the driver due to the torque variation accompanied by the change in the air/fuel ratio is eliminated. Accordingly, a reduction in the actual fuel cost and a promotion of the drivability can both be achieved.